N-aminopyridone dyes

ABSTRACT

Pyridone dyes useful for thermal transfer have the formula ##STR1## wherein R 1 , R 2 , R 3 , Y, X and Z are defined in the specification.

The present invention relates to novel pyridone dyes of the formula I ##STR2## where

R¹ is hydrogen or C₁ -C₄ -alkyl,

R² and R³ are identical or different and each is, independently of the other, hydrogen, substituted or unsubstituted C₁ -C₁₂ -alkyl, C₅ -C₇ -cycloalkyl, substituted or unsubstituted phenyl, substituted or unsubstituted pyridyl, substituted or unsubstituted C₁ -C₁₂ -alkanoyl, C₁ -C₁₂ -alkoxycarbonyl, substituted or unsubstituted C₁ -C₁₂ -alkylsulfonyl, C₅ -C₇ -cycloalkylsulfonyl, substituted or unsubstituted phenylsulfonyl, substituted or unsubstituted pyridylsulfonyl, substituted or unsubstituted benzoyl, pyridylcarbonyl or thienylcarbonyl or are together with the nitrogen atom to which they are bonded unsubstituted or C₁ -C₄ -alkyl-substituted succinimido, unsubstituted or C₁ -C₄ -alkyl-substituted phthalimido or a five- or six-membered saturated heterocyclic radical which may contain further hetero atoms,

X is CH or nitrogen,

Y is cyano or a radical of the formula CO--W, CO--OW or CO--NHW where W is hydrogen, C₁ -C₈ -alkyl which may be substituted and which may be interrupted by one or two oxygen atoms in ether function, C₅ -C₇ -cycloalkyl, phenyl or tolyl, and

Z is an aromatic carbocyclic or heterocyclic radical, and to a process for the thermal transfer thereof.

EP-A-416,434 discloses pyridone dyes. However, it has been found that the prior art dyes still have deficiencies in their application properties.

It is an object of the present invention to provide novel N-aminopyridone dyes which are advantageous for thermal transfer.

We have found that this object is achieved by the pyridone dyes of the formula I defined at the beginning.

Aromatic carbocyclic or heterocyclic radicals Z are derived for example from the aniline, aminonaphthalene, indole, quinoline, benzoxazine or aminothiazole series.

Preference is given to pyridone dyes of the formula I where

Z is a radical of the formula ##STR3## where

n is 0 or 1,

R⁴ is hydrogen, methyl, methoxy, C₁ -C₄ -alkylsulfonylamino, mono- or di-C₁ -C₄ -alkylaminosulfonylamino or the radical --NHCOR¹⁰ or --NHCO₂ R¹⁰, where R¹⁰ is phenyl, benzyl, tolyl or C₁ -C₈ -alkyl, which may be interrupted by one or two oxygen atoms in ether function,

R⁵ is hydrogen, methyl, methoxy or ethoxy,

R⁶ and R⁷ are identical or different and each is independently of the other hydrogen, C₁ -C₈ -alkyl, which may be substituted and which may be interrupted by one or two oxygen atoms in ether function, C₃ -C₄ -alkenyl, C₅ -C₇ -cycloalkyl, phenyl or tolyl or are together with the nitrogen atom to which they are bonded a five- or six-membered saturated heterocyclic radical which may contain further hetero atoms,

R⁸ is halogen and

R⁹ is hydrogen, halogen, C₁ -C₆ -alkyl, substituted or unsubstituted phenyl, substituted or unsubstituted benzyl, cyclohexyl, thienyl, hydroxyl or mono-C₁ -C₈ -alkylamino, and

R¹ is as defined in claim 1.

Any alkyl appearing in the formula of the pyridone dyes according to the present invention may be either straight-chain or branched.

Any substituted alkyl appearing in the formula of the pyridone dyes according to the present invention may have as substituents for example cyano, phenyl, tolyl, C₁ -C₆ -alkanoyloxy, C₁ -C₄ -alkoxycarbonyl or C₁ -C₄ -alkoxycarbonyloxy, the last-mentioned of which may in turn be substituted in the alkoxy group by phenyl or C₁ -C₄ -alkoxy.

Any substituted phenyl appearing in the formula of the pyridone dyes according to the present invention may have as substituents for example C₁ -C₄ -alkyl or C₁ -C₄ -alkoxy.

W, R¹, R², R³, R⁶, R⁷, R⁹ and R¹⁰ are each for example methyl, ethyl, propyl, isopropyl, butyl, isobutyl or sec-butyl.

W, R⁶, R⁷, R⁹ and R¹⁰ may each also be for example pentyl, isopentyl, neopentyl, tert-pentyl, hexyl or 2-methylpentyl.

W, R⁶, R⁷ and R¹⁰ may each also be for example heptyl, octyl, isooctyl or 2-ethylhexyl.

R² and R³ may also be for example nonyl, isononyl, decyl, isodecyl, undecyl or dodecyl (the above designations isooctyl, isononyl and isodecyl are trivial names derived from alcohols obtained by the oxo process--cf. Ullmanns Encyklopadie der technischen Chemie, 4th Edition, Volume 7, pages 215 to 217, and also Volume 11, pages 435 and 436), phenyl, 2-, 3- or 4-methylphenyl, 2-, 3- or 4-methoxyphenyl, pyridyl, 2-, 3- or 4-methylpyridyl, 2-, 3- or 4-methoxypyridyl, formyl, acetyl, propionyl, butyryl, isobutyryl, pentanoyl, hexanoyl, heptanoyl, octanoyl, 2-ethylhexanoyl, methoxycarbonyl, ethexycarbonyl, propoxycarbonyl, isopropoxycarbonyl, butoxycarbonyl, methylsulfonyl, ethylsulfonyl, propylsulfonyl, isopropylsulfonyl, butylsulfonyl, cyclopentylsulfonyl, cyclohexylsulfonyl, cycloheptylsulfonyl, phenylsulfonyl, tolylsulfonyl, pyridylsulfonyl, benzoyl, 2-, 3- or 4-methylbenzoyl, 2-, 3- or 4-methoxybenzoyl, thien-2-ylcarbonyl or thien-3-ylcarbonyl.

W, R⁵, R⁷ and R¹⁰ may each also be for example 2-methoxyethyl, 2- or 3-methoxypropyl, 2-ethoxyethyl, 2- or 3-ethoxypropyl, 2-propoxyethyl, 2- or 3-propoxypropyl, 2-butoxyethyl, 2- or 3-butoxypropyl, 3,6-dioxaheptyl or 3,6-dioxaoctyl.

W, R², R³, R³ and R⁷ may each also be for example 2-cyanoethyl, 2- or 3-cyanopropyl, 2-acetyloxyethyl, 2- or 3-acetyloxypropyl, 2-isobutyryloxyethyl, 2- or 3-isobutyryloxypropyl, 2-methoxycarbonylethyl, 2- or 3-methoxycarbonylpropyl, 2-ethoxycarbonylethyl, 2- or 3-ethoxycarbonylpropyl, 2-methoxycarbonyloxyethyl, 2- or 3-methoxycarbonyloxypropyl, 2-ethoxycarbonyloxyethyl, 2- or 3-ethoxycarbonyloxypropyl, 2-butoxycarbonyloxyethyl, 2- or 3-butoxycarbonyloxypropyl, 2-(2-phenylethoxycarbonyloxy)ethyl, 2-or 3-(2-phenylethoxycarbonyloxy)propyl, 2-(2-ethoxyethoxycarbonyloxy)ethyl, 2- or 3-(2-ethoxyethoxycarbonyloxy)propyl, benzyl, 2-methylbenzyl, 1- or 2 -phenylethyl, cyclopentyl, cyclohexyl, cycloheptyl or 2-, 3- or 4-methylphenyl.

R⁴ is for example methylsulfonylamino, ethylsulfonylamino, propylsulfonylamino, isopropylsulfonylamino, butylsulfonylamino, mono- or dimethylaminosulfonylamino, mono- or diethylaminosulfonylamino, mono- or dipropylaminosulfonylamino, mono- or diisopropylaminosulfonylamino, mono- or dibutylaminosulfonylamino or (N-methyl-N-ethylaminosulfonyl) amino.

R⁹ may also be for example, like R⁸, fluorine, chlorine or bromine.

R⁹ may also be for example phenyl, 2-methylphenyl, 2,4-dimethylphenyl, 2-methoxyphenyl, 2,4-dimethoxyphenyl, benzyl, 2-methylbenzyl, 2,4-dimethylbenzyl, 2-methoxybenzyl, 2,4-dimethoxybenzyl, methylamino, ethylamino, propylamino, isopropylamino, butylamino, pentylamino, hexylamino, heptylamino, octylamino or 2-ethylhexylamino.

R⁸ and R⁷ may each also be for example allyl or methallyl.

R² combined with R³ or R⁶ with R⁷ and with the nitrogen atom to which they are bonded in a five- or six-membered saturated heterocyclic radical which may have further hetero atoms may be for example pyrrolidinyl, piperidinyl, morpholinyl, piperazinyl or N-(C₁ -C₄ -alkyl)piperazinyl.

Particular preference is given to dyes of the formula I where Z is a radical of the formula IIa, IIc, IIl, IIm, IIn, IIo or IIp, in particular a radical of the formula IIc or IIl.

Of particular noteworthiness are dyes of the formula IIIa ##STR4## where

X is CH or nitrogen,

L¹ and L² are each independently of the other hydrogen, C₁ -C₈ -alkyl, phenyl, tolyl, C₁ -C₈ -alkylcarbonyl, C₁ -C₈ -alkylsulfonyl, phenylsulfonyl, tolylsulfonyl, pyridylsulfonyl, benzoyl, methylbenzoyl, pyridycarbonyl or thienylcarbonyl,

L³ is hydrogen, methyl, methoxy or the radical --NHCOR¹⁰ or --NHCO₂ R¹⁰, where R¹⁰ is phenyl, benzyl, tolyl or C₁ -C₈ -alkyl, which may be interrupted by one or two oxygen atoms in ether function,

L⁴ and L⁵ are each independently of the other hydrogen, C₁ -C₈ -alkyl, 2-cyanoethyl, benzyl, C₁ -C₄ -alkanoyloxy-C₁ -C₄ -alkyl, C₁ -C₄ -alkoxycarbonyl-C₁ -C₄ -alkyl or C₁ -C₄ -alkoxycarbonyloxy-C₁ -C₄ -alkyl and

L⁵ is hydrogen or methyl.

Also of particular noteworthiness are dyes of the formula IIIb ##STR5## where X is CH or nitrogen, L⁷ is C₁ -C₆ -alkyl, phenyl, tolyl, benzyl, cyclohexyl or thienyl, and L¹, L², L⁴, L⁵ and L⁶ are each as defined under formula IIIa.

Of very particular noteworthiness are dyes of the formula IIIa where L¹ and L² are each independently of one another C₁ -C₈ -alkylcarbonyl, benzoyl, methylbenzoyl or thienylcarbonyl.

Also of very particular noteworthiness are dyes of the formula IIIb where X is CH.

The novel pyridone dyes of the formula I can be prepared in a conventional manner.

For example, formyl (X═CH) or nitroso compounds (X═N) of the formula IV

    Z--X═O                                                 (IV)

where Z is as defined above, can be condensed with a pyridone of the formula V ##STR6## where R¹, R² and Y are each as defined above, in an inert solvent in the presence of a catalyst.

Suitable inert solvents are for example toluene, chlorobenzene, nitrobenzene, methyl benzoate, ethyl benzoate, methylene chloride, chloroform, carbon tetrachloride, 1,1-dichloroethane, 1,2-dichloroethane, 1,1,1-trichloroethane, isobutanol, acetic acid, propionic acid, xylene, benzene and dichlorobenzene.

Suitable catalysts are for example p-toluene-sulfonic acid, sulfuric acid, acetic anhydride, propionic anhydride, benzoic anhyride and N,N'-dicyclohexylcarbodiimide. These catalysts can be used in an amount of from 1 to 50, preferably from 1 to 10, mole equivalent, based on a mole equivalent of pyridone V.

The resulting dyes of formula Ia ##STR7## where R¹, R², X, Y and Z are each as defined above, can be for example converted into the pyridone dyes of the formula I by acylation with a carboxylic anhydride of the formula VI or a compound of the formula VII

    R.sup.11 --CO--O--CO--R.sup.11                             (VI)

    R.sup.11 --CO--R.sup.12                                    (VII)

where R¹¹ is C₁ -C₁₁ -alkyl, substituted or unsubstituted with phenyl or thienyl, and R¹² is a leaving group, for example chlorine, bromine, methylsulfonate, trifluoromethylsulfonate or o- or p-toluenesulfonate, in an inert solvent in the presence or absence of a base.

Suitable bases are for example amines, such as triethylamine, tributylamine, pyridine, p-dimethylaminopyridine, alkali metal bicarbonates such as sodium or potassium bicarbonate, alkali metal carbonates, such as sodium or potassium carbonate, or alkali metal salts of lower carboxylic acids, such as sodium or potassium acetate or sodium or potassium propionate. The amount of base used per mole equivalent of dye Ia is in general from 1 to 50, preferably from 1 to 10, mole equivalent.

However, it is also possible to prepare the dyes of the formula I in a one-pot synthesis by reacting the compounds IV with the pyridone V in the presence of a compound of the formula VI or VII and in the presence or absence of a base. Suitable inert solvents and bases are the abovementioned compounds.

It is also possible to couple amines of the formula VI

    Z--NH.sub.2                                                (VI)

where Z is as defined above, oxidatively with pyridones of the formula V (see for example U.S. Pat. No. 4,695,287).

It is a further object of the present invention to provide a novel process for the thermal transfer of dyes.

In the thermal transfer printing process, a transfer sheet, which contains a thermally transferable dye in one or more binders with or without suitable assistants, on a substrate, is heated from the back with an energy source, for example a thermal head or a laser, in the form of short heating pulses (durations fractions of a second), causing the dye to migrate out of the transfer sheet and diffuse into the surface coating of a receiving medium. The essential advantage of this process is that the amount of dye to be transferred, and hence the color gradation, is readily controlled by controlling the energy to be emitted by the energy source.

In general, color recording involves the use of the three subtractive primaries yellow, magenta and cyan (with or without black).

To permit optimal color recording, the dyes must have the following properties:

ready thermal transferability,

minimal tendency to migrate within or out of the surface coating of the receiving medium at room temperature,

high thermal and photochemical stability and resistance to moisture and chemicals,

suitable hues for subtractive color mixing,

a high molar absorption coefficient, and

no tendency to crystallize out on storage of the transfer sheet.

It is known from experience that it is very difficult to meet all these requirements at one and the same time.

For this reason most of the dyes used for thermal transfer printing do not meet the required property profile.

We have found that the further object is achieved by a process for transferring a pyridone dye from a transfer to plastic-coated paper with the aid of an energy source by using a transfer on which there is or are located one or more dyes of the formula I.

Compared with the dyes used in existing processes, the dyes of the formula I transferred in the process of the present invention are in general notable for improved migration properties in the receiving medium at room temperature, a readier thermal transferability, higher thermal and photochemical stability, readier industrial accessibility, better resistance to moisture and chemicals, higher color strength, better solubility or better suitability for subtractive color mixing (higher cleanness of hue, better shape of absorption band).

To prepare the dye transfers required for the process of the present invention, the dyes are incorporated in a suitable organic solvent or in mixtures of solvents with one or more binders, in the presence or absence of assistants, to form a printing ink. It preferably contains the dye in a molecularly dispersed, i.e. dissolved form. The printing ink can then be doctored onto the inert substrate of the later transfer and air dried.

Suitable organic solvents for the dyes I are for example those in which the solubility of the dyes I at 20° C. is greater than 1% by weight, preferably greater than 5% by weight.

Examples are ethanol, propanol, isobutanol, tetrahydrofuran, methylene chloride, methyl ethyl ketone, cyclopentanone, cyclohexanone, toluene, chlorobenzene and mixtures thereof.

As binders it is possible to use any resin or polymer material which is soluble in organic solvents and capable of binding the dye to the inert substrate in such a way that it will not rub off. Preference is here given to those binders which, after the air drying of the printing ink, hold the dye in the form of a clear, transparent film in which no visible crystallization of the dye occurs.

Such binders are mentioned for example in EP-A-441,282 or in the relevant patent applications cited therein. Saturated linear polyesters are also suitable.

Preferred binders are ethylcellulose, ethyl-hydroxyethylcellulose, polyvinyl butyrate, polyvinyl acetate, cellulose propionate and saturated linear polyesters.

The weight ratio of binder to dye ranges in general from 1:1 to 10:1.

Suitable assistants are for example release agents as mentioned in EP-A-441,282 or in the relevant patent applications cited therein. It is also possible to use organic additives which prevent crystallization of the transfer dye in the course of storage or heating of the color ribbon, for example cholesterol or vanillin.

Suitable inert substrates are described for example in EP-A-441,282 or in the relevant patent applications cited therein. The thickness of the substrate is in general from 3 to 30 μm, preferably from 5 to 10 μm.

As dye receptor layer it is basically possible to use any heat stable plastics layer which possesses affinity for the dyes to be transferred, e.g. modified polycarbonates or polyesters. Further details may be found for example in EP-A-441,282 or in the relevant patent applications cited therein.

The transfer is effected by means of an energy source, for example by means of a laser or by means of a thermal head that must be heatable to ≧300° C. in order for dye transfer to take place within the time range t: 0<t<15 msec. In the course of transfer, the dye migrates out of the transfer sheet and diffuses into the surface coating of the receiving medium.

Mixtures of the noveldyes I with one another are also particularly suitable.

The dyes according to the present invention are also advantageously suitable for dyeing synthetic materials, for example polyesters, polyamides or polycarbonates. Of particular suitability are textile fabrics made of polyester or polyamide or polyester-cotton blend fabrics.

The novel dyes are also advantageous for preparing color filters as described for example in EP-A-399,473.

Finally, they can also be advantageously used as colorants for preparing toners for electrophotography.

Embodiments of the invention will now be more particularly described by way of example.

Preparation of dyes

EXAMPLE 1 ##STR8##

13.1 g of 3-acetylamino-N,N-dibutyzanizine were nitrosated with sodium nitrite in an aqueous medium acidified with hydrochloric acid. After addition of 20% by weight ammonia solution in water to pH 8, the compound of the formula ##STR9## was taken up in methylene chloride. The organic phase was separated off in a separating funnel and combined with a solution of 15.5 g of the pyridone ##STR10## in 30 ml of acetic anhydride.

After the methylene chloride had been distilled off, the residue was briefly heated to 90° C. and then cooled down to room temperature. Then 100 ml of isopropanol and 50 ml of methanol were added, and the dye was precipitated with about 5 ml of water. Filtering off with suction and thorough washing with methanol left 18.1 g (64% of theory) of the above dye in a spectrally pure form.

Melting point: 170°-174° C.

λ_(max) (tetrahydrofuran): 590 nm

(methylene chloride): 598 nm.

EXAMPLE 2 ##STR11##

15.5 g of the pyridone described in Example 1 were stirred with 15.1 g of 2-(N-butyl-N-ethylamino)-4-phenyl-5-formylthiazole, 0.5 g of β-alanine and also 2.0 g of p-toluenesulfonic acid in 65 ml of ethyl acetate at room temperature for 3.5 hours. Then the mixture was heated at 5° C. for 30 minutes. After cooling down to room temperature, the dye was filtered off with suction, washed neutral with a little methanol and water and dried under reduced pressure at 95° C. The yield of spectrally pure product was 17.6 g (63% of theory).

Melting point: 141° C.

λ_(max) (tetrahydrofuran): 532 nm

(methylene chloride): 537 nm.

The same method was used to obtain the dyes listed below in Tables 1 to 3. In these tables, the entries in the column headed R³ are designations of the formulae given in the description.

                                      TABLE 1                                      __________________________________________________________________________      ##STR12##                                                                     Ex. No.                                                                             R.sup.3                                                                           X  R.sup.4                                                                              R.sup.5                                                                          R.sup.6                                                                           R.sup.7                                                                            R.sup.9                                                                              λ.sub.max [nm] in CH.sub.2              __________________________________________________________________________                                     Cl.sub.2                                       3    IIl                                                                               CH --    --                                                                               C.sub.2 H.sub.5                                                                   C.sub.4 H.sub.9                                                                    C.sub.6 H.sub.5                                                                      537                                            4    IIl                                                                               CH --    --                                                                               C.sub.2 H.sub.5                                                                   C.sub.6 H.sub.13                                                                   CH(CH.sub.3).sub.2                                                                   524                                            5    IIa                                                                               N  NHCOCH.sub.3                                                                         H C.sub.4 H.sub.9                                                                   C.sub.4 H.sub.9                                                                    --    599                                            6    IIp                                                                               CH --    --                                                                               CH.sub.3                                                                          --  --    521                                            7    IIl                                                                               CH --    --                                                                               CH.sub.3                                                                          C.sub.6 H.sub.11                                                                   C.sub.6 H.sub.5                                                                      537                                            8    IIl                                                                               CH --    --                                                                               C.sub.2 H.sub.5                                                                   C.sub.2 H.sub.5                                                                    CH(CH.sub.3).sub.2                                                                   524                                            9    IIp                                                                               CH --    --                                                                               CH.sub.3                                                                          --  --    521                                            __________________________________________________________________________

                                      TABLE 2                                      __________________________________________________________________________      ##STR13##                                                                     Ex. No.                                                                             R.sup.3                                                                           X  R.sup.4                                                                          R.sup.5                                                                           R.sup.6                                                                               R.sup.7                                                                              R.sup.9                                                                           λ.sub.max [nm] in CH.sub.2              __________________________________________________________________________                                     Cl.sub.2                                       10   IIl                                                                               CH --                                                                               -- CH(CH.sub.3).sub.2                                                                    CH(CH.sub.3).sub.2                                                                   C.sub.6 H.sub.5                                                                   538                                            11   IIp                                                                               CH --                                                                               -- CH.sub.3                                                                              --    -- 522                                            12   IIc                                                                               CH H CH.sub.3                                                                          CH.sub.3                                                                              --    -- 534                                            13   IIa                                                                               CH H H  C.sub.2 H.sub.4 C.sub.6 H.sub.5                                                       C.sub.2 H.sub.4 CN                                                                   -- 537                                            14   IIl                                                                               CH --                                                                               -- C.sub.6 H.sub.11                                                                      C.sub.6 H.sub.11                                                                     C.sub.6 H.sub.5                                                                   542                                            15   IIp                                                                               CH --                                                                               -- CH.sub.3                                                                              --    -- 522                                            16   IIo                                                                               CH --                                                                               -- --     --    H  514                                            17   IIl                                                                               N  --                                                                               -- C.sub.2 H.sub.5                                                                       C.sub.2 H.sub.5                                                                      C.sub.6 H.sub.5                                                                   586                                            18   IIc                                                                               N  H H  C.sub.2 H.sub.5                                                                       --    -- 599                                            __________________________________________________________________________

                                      TABLE 3                                      __________________________________________________________________________      ##STR14##                                                                                                                             λ.sub.max                                                               [nm]                   Ex. No.                                                                             R.sup.1                                                                           R.sup.3                                                                           X  R.sup.4                                                                              R.sup.5                                                                           R.sup.6   R.sup.7                                                                              R.sup.8 R.sup.9  in CH.sub.2                                                                    Cl.sub.2               __________________________________________________________________________     19   CH.sub.3                                                                          IIl                                                                               N  --    -- CH(CH.sub.3).sub.2                                                                       CH(CH.sub.3).sub.2                                                                   --      C.sub.6 H.sub.5                                                                         587                    20   CH.sub.3                                                                          IIl                                                                               CH --    -- C.sub.6 H.sub.11                                                                         CH.sub.3                                                                             --      C.sub.6 H.sub.5                                                                         535                    21   CH.sub.3                                                                          IIl                                                                               CH --    -- CH(CH.sub.3).sub.2                                                                       CH(CH.sub.3).sub.2                                                                   --      C.sub.6 H.sub.5                                                                         538                    22   CH.sub.3                                                                          IIc                                                                               CH H     CH.sub.3                                                                          CH.sub.3  --    --      --       536                    23   CH.sub.3                                                                          IIl                                                                               CH --    -- C.sub.4 H.sub.9                                                                          C.sub.4 H.sub.9                                                                      --      C.sub.6 H.sub.5                                                                         537                    24   CH.sub.3                                                                          IIl                                                                               CH --    -- C.sub.2 H.sub.5                                                                          C.sub.2 H.sub.5                                                                      --      C.sub.6 H.sub.5                                                                         534                    25   CH.sub.3                                                                          IIl                                                                               CH --    -- C.sub.6 H.sub.11                                                                         C.sub.2 H.sub.5                                                                      --      C.sub.6 H.sub.5                                                                         540                    26   CH.sub.3                                                                          IIl                                                                               CH --    -- C.sub.6 H.sub.11                                                                         C.sub.6 H.sub.11                                                                     --      C.sub.6 H.sub.5                                                                         541                    27   CH.sub.3                                                                          IIa                                                                               N  NHCOCH.sub.3                                                                         H  C.sub.2 H.sub.5                                                                          C.sub.2 H.sub.5                                                                      --      --       595                    28   CH.sub.3                                                                          IIl                                                                               CH --    -- C.sub.2 H.sub.5                                                                          C.sub.4 H.sub.9                                                                      --      C.sub.6 H.sub.5                                                                         537                    29   CH.sub.3                                                                          IIl                                                                               CH --    -- C.sub.2 H.sub.5                                                                          C.sub.2 H.sub.5                                                                      --      CH(CH.sub.3).sub.2                                                                      524                    30   CH.sub.3                                                                          IIc                                                                               CH H     H  C.sub.2 H.sub.4 CO.sub.2 C.sub.2 H.sub.5                                                 --    --      --       541                    31   CH.sub.3                                                                          IIa                                                                               N  CH.sub.3                                                                             H  C.sub.4 H.sub.9                                                                          C.sub.4 H.sub.9                                                                      --      --       678                    32   CH.sub.3                                                                          IIj                                                                               CH --    -- C.sub.2 H.sub.4 OC.sub.2 H.sub.4 *.sup.)                                                       Cl      --       557                    33   CH.sub.3                                                                          IIj                                                                               CH --    -- C.sub.4 H.sub.8 **.sup.)                                                                       PCH.sub.3 C.sub.6 H.sub.4                                                              --       544                    34   CH.sub.3                                                                          IIl                                                                               CH --    -- C.sub.3 H.sub.7                                                                          C.sub.3 H.sub.7                                                                      --      PCH.sub.3 OC.sub.6                                                                      534ub.4                35   H  IIl                                                                               CH --    -- C.sub.4 H.sub.9                                                                          C.sub.4 H.sub.9                                                                      --      C.sub.6 H.sub.5                                                                         545                    __________________________________________________________________________      *.sup.) n - 1                                                                  **.sup.) n = 0                                                           

                  TABLE 4                                                          ______________________________________                                          ##STR15##                                                                                                                   λ.sub.max [nm]            Ex.                                           in                               No.  R.sup.3                                                                               X      R.sup.4 R.sup.5                                                                            R.sup.6                                                                             R.sup.7                                                                             R.sup.9                                                                             CH.sub.2 Cl.sub.2                ______________________________________                                         36   IIl    CH     --      --  C.sub.4 H.sub.9                                                                     C.sub.4 H.sub.9                                                                     C.sub.6 H.sub.5                                                                     537                              37   IIa    N      CH.sub.3                                                                               H   C.sub.2 H.sub.5                                                                     C.sub.4 H.sub.9                                                                     --   713                              38   IIa    N      NHCOCH.sub.3                                                                           H   C.sub.2 H.sub.5                                                                     C.sub.2 H.sub.5                                                                     --   593                              ______________________________________                                    

Embodiments of the invention will now be more particularly described by way of example.

Preparation of dyes

EXAMPLE 39

a) ##STR16##

349.7 g of 1-benzoylamino-2-hydroxy-4-methyl-5-cyanopyrid-6-one were suspended in 1.5 l of toluene and 13 g of p-toluenesulfonic acid. 529.3 g of 78% strength by weight of 2-(di-n-butylamino)-4-phenyl-5-formylthiazole were added dropwise at 70° C. The reaction mixture was refluxed for 6 hours under a water separator. After 1 l of toluene had been distilled off, the reaction mixture was cooled down to room temperature. The precipitate was filtered off with suction and dried at 50° C. under reduced pressure. This left 692.3 g (94% of theory) of the abovementioned compound (Q═H) having a melting point of 236° C.

(Using isobutanol as solvent the compound was obtained in a 76% yield.)

b) 567 g of the compound described under a) were suspended in 800 ml of acetic anhydride and heated at the boil for 2 hours. The resulting solution was cooled down to 60° C., which brought down a precipitate, and then diluted with 450 ml of methanol. The precipitate was filtered off with suction and washed with methanol and water. Drying under reduced pressure at 50° C. left 458.3 g (75% of theory) of the abovementioned compound (Q═COCH₃) having a melting point of 193° C.

(λ_(max) =measured in CH₂ Cl₂ : 537 nm)

The same method was used to obtain the dyes listed below in Table 5.

                                      TABLE 5                                      __________________________________________________________________________      ##STR17##                                                                     Ex. No.                                                                             Z                     R.sup.2                                                                             R.sup.3  λ.sub.max (in CH.sub.2                                                  Cl.sub.2) or mp.                      __________________________________________________________________________     40                                                                                   ##STR18##            COC.sub.6 H.sub.5                                                                   COC.sub.2 H.sub.5                                                                       224° C.                        41                                                                                   ##STR19##            COC.sub.6 H.sub.5                                                                   COC.sub.6 H.sub.5                                                                       130-134° C.                    42                                                                                   ##STR20##            COCH.sub.3                                                                           ##STR21##                                                                              539 nm                                43                                                                                   ##STR22##            COC.sub.6 H.sub.5                                                                   COCH.sub.3                                                                              537 nm                                44                                                                                   ##STR23##            COC.sub.6 H.sub.5                                                                   COCH.sub.3                                                                              524 nm                                45                                                                                   ##STR24##            COCH.sub.3                                                                           ##STR25##                                                                              537 nm                                46                                                                                   ##STR26##            COC.sub.6 H.sub.5                                                                   COCH.sub.3                                                                              536 nm                                47                                                                                   ##STR27##            COC.sub.6 H.sub.5                                                                   COCH.sub.3                                                                               565 nm*                              48                                                                                   ##STR28##            COCH.sub.3                                                                           ##STR29##                                                                              521 nm                                49                                                                                   ##STR30##            COC.sub.6 H.sub.5                                                                   COCH.sub.3                                                                              549 nm                                __________________________________________________________________________      *measured in tetrahydrofuran                                             

EXAMPLE 50 ##STR31##

65 g of 2-(N-ethyl-N-cyclohexylamino)-4-phenyl-5-formylthiazole and 53.8 g of 1-benzoylamino-2-hydroxy-4-methyl-5-cyanopyrid-6-one were added to 200 ml of acetic anhydride, heated with stirring to reflux temperature (136° C.) in the course of 15 minutes and held at that reflux temperature for 15 minutes. The mixture was then cooled down to 28° C. and the precipitate was filtered off with suction. It was washed portionwise with 350 ml of methanol and then with 1000 ml of water. It was then dried at 75° C. under reduced pressure.

This left 103 g of a spectrally pure magenta mixture having a melting point of 258° C. and, according to HPLC, the following composition:

    ______________________________________                                                Q = COCH.sub.3  66%                                                            Q = H           33%                                                     ______________________________________                                    

λ_(max) (in methylene chloride): 538 nm.

EXAMPLE 51

Example 51 was carried out by a method similar to that of Example 50 except that the refluxing was carried out for 4 hours. This resulted in complete acetylation (Q═COCH₃). λ_(max) (in methylene chloride): 540 nm.

This same method was used to obtain the dyes listed below in Table 6.

                                      TABLE 6                                      __________________________________________________________________________      ##STR32##                                                                     Ex. No.                                                                             Z                         X  R.sup.2                                                                               R.sup.3                                                                             W    λ.sub.max (in                                                           CH.sub.2 Cl.sub.2) or                                                          mp.                         __________________________________________________________________________     52                                                                                   ##STR33##                CH COCH.sub.3                                                                            COC.sub.6 H.sub.5                                                                   CN   536                         53                                                                                   ##STR34##                CH COCH.sub.3                                                                            COCH.sub.3                                                                          CN   536                         54                                                                                   ##STR35##                N  COCH.sub.3                                                                            COC.sub.6 H.sub.5                                                                   CN   586                         55                                                                                   ##STR36##                CH COC.sub.2 H.sub.5                                                                     COC.sub.6 H.sub.5                                                                   CN   537                         56                                                                                   ##STR37##                CH COC.sub.3 H.sub.7                                                                     COC.sub.6 H.sub.5                                                                   CN   537                         57                                                                                   ##STR38##                CH COCH(CH.sub.3).sub.2                                                                  COC.sub.6 H.sub.5                                                                   CN   537                         58                                                                                   ##STR39##                CH COCH(CH.sub.3).sub.2                                                                  COC.sub.6 H.sub.5                                                                   CN   534                         59                                                                                   ##STR40##                CH COCH.sub.3                                                                            COC.sub.6 H.sub.5                                                                   CN   539                         60                                                                                   ##STR41##                CH COCH.sub.3                                                                            COC.sub.6 H.sub.5                                                                   CN   555                         61                                                                                   ##STR42##                CH COCH.sub.3                                                                            COC.sub.6 H.sub.5                                                                   CN   556                         62                                                                                   ##STR43##                CH COC.sub.6 H.sub.5                                                                     COC.sub.6 H.sub.5                                                                   CN   537                         63                                                                                   ##STR44##                N  COCH.sub.3                                                                            COC.sub.6 H.sub.5                                                                   CN   682                         64                                                                                   ##STR45##                CH COCH.sub.3                                                                            COC.sub.6 H.sub.5                                                                   CN   547                         65                                                                                   ##STR46##                CH COCH.sub.3                                                                            COC.sub.6 H.sub.5                                                                   CN   534                         66                                                                                   ##STR47##                CH COCH.sub.3                                                                            COC.sub.6 H.sub.5                                                                   CN   534                         67                                                                                   ##STR48##                CH COCH.sub.3                                                                            COC.sub.6 H.sub.5                                                                   CN   549                         68                                                                                   ##STR49##                CH COCH.sub.3                                                                            COCH.sub.3                                                                          CN   537                         69                                                                                   ##STR50##                CH COC.sub.6 H.sub.5                                                                     COCH.sub.3                                                                          CO.sub.2 CH.sub.3                                                                   518                         70                                                                                   ##STR51##                CH COC.sub.6 H.sub.5                                                                     COCH.sub.3                                                                          COCH.sub.3                                                                          530                         __________________________________________________________________________

Transfer of dyes (use)

I.

To be able to examine the transfer behavior of the dyes quantitatively and in a simple manner, the thermal transfer was carried out with large hot plates with the transfer temperature being varied within the range 50° C.<T<120° C. while the transfer time was fixed at 2 minutes.

α) General recipe for coating the substrate with dye:

1 g of binder was dissolved in 8 ml of 8:2 v/v toluene/ethanol at 40°-50° C. A solution of 0.25 g of dye in 50 ml of tetrahydrofuran was added with stirring and any insolubles were filtered off. The print paste thus obtained was applied to a polyester film (thickness: 6-10 μm) with an 80 μm doctor and dried with a hairdryer.

β) Test of thermal transferability

The dyes used were tested as follows. The polyester film donor containing the in-test dye in the coated front was placed face down on commercially available (see below for details) paper (receptor) and pressed down. Donor/receptor were then wrapped in aluminum foil and heated between two hot plates at various temperatures T (within the temperature range 50° C.<T<120° C.). The amount of dye which diffuses into the bright plastics layer of the receptor is proportional to the optical density (=absorbance A). The latter was determined photometrically. The plot of the logarithm of the absorbance A of the colored receptor papers measured within the temperature range from 50° to 120° C. against the reciprocal of the corresponding absolute temperature is a straight line from whose slope it is possible to calculate the activation energy ΔE_(T) for the transfer experiment: ##EQU1## The characterization was completed by additionally taking from the plots the temperature T^(*) [°C.] at which the absorbance A of the colored receptor papers attains the value 1.

The dyes listed below in Table 7 were processed according to α) and the resulting dye-coated substrates were tested in respect of their transfer behavior according to β). The table also shows in each case the thermal transfer parameters T^(*) and ΔE_(T).

The receiving medium or receptor used was Hitachi color video print paper of grade VY-S. The binder used was Vylon.sup.• 290 from Toyobo.

II.

General method:

a) 10 g of dye are stirred with or without brief heating to 80°90° C. into 100 g of a 10% strength by weight solution of a binder (Vylon.sup.• 290 from Toyobo) in 4.5:2:2 v/v/v methyl ethyl ketone/toluene/cyclohexanone.

The printing ink is applied with a 6 μm doctor blade to a polyester sheet 6 μm in thickness whose back has been coated with a suitable slipping layer and blown dry with a hairdryer in the course of 1 minute. Before the color ribbon can be printed, it must subsequently air dry for at least 24 hours, since residual solvent can impair the printing process.

b) The color ribbons are printed on a computer controlled experimental setup equipped with a conventional thermal printing head onto Hitachi VY-S video print paper.

The voltage is varied to control the energy output of the thermal printing head, while the pulse duration is set to 7 ms and only one pulse is emitted at a time. The emitted energy ranges from 0.71 to 1.06 mJ/dot.

Since the degree of coloration is directly proportional to the energy supply, it is possible to produce a color wedge for spectroscopic evaluation.

A plot of the depth of shade against the energy supply is used to determine the Q^(*) value (=energy in mJ/dot for absorbance 1) and the slope m in 1/mJ.

The results obtained are listed below in Table 8, which additionally shows the full width at half maximum (FWHM), measured on Hitachi VY-S video print paper, and the weight-specific extinction coefficient (f), measured in methylene chloride.

                  TABLE 7                                                          ______________________________________                                          ##STR52##                                                                               ##STR53##                                                                                  ##STR54##                                                                               ##STR55##                                       ______________________________________                                         71       3           92       15                                               72       4           82       12                                               73       5           78       10                                               74       6           69       10                                               75       7           90       10                                               76       8           70       11                                               77       2           85       16                                               78       10          68       14                                               79       11          63       13                                               80       12          77       9                                                81       1           73       12                                               82       13          91       10                                               83       14          82       13                                               84       19          67       11                                               85       20          54       11                                               86       21          62       12                                               87       22          77       10                                               88       25          72       11                                               89       9           69       10                                               90       15          63       13                                               ______________________________________                                    

                  TABLE 8                                                          ______________________________________                                          ##STR56##                                                                           ##STR57##                                                                               ##STR58##                                                                               ##STR59##                                                                             ##STR60##                                                                             ##STR61##                                ______________________________________                                         91   39       0.87     3.30   2527   190                                       92   51       0.97     2.30   2462   154                                       93   42       0.95     2.86   2134                                             94   43       0.94     2.48   2536   161                                       95   44       0.89     3.07   2343   185                                       96   45       0.90     2.52   2150                                             97   46       0.95     2.63   2821                                             98   48       1.29     1.22   2358                                             99   49       1.07     2.01   3394                                             100  50       1.03     2.21   2517   164                                       101  16       1.09     1.90   2490                                             102  17       1.38     1.26   2740   116                                       103  18       1.34     1.49   4352                                             104  23       1.04     2.02   2608   129                                       105  24       1.19     1.59   2596   155                                       106  26       1.70     1.35   2310                                             107  27       1.65     1.40   3765                                             108  28       1.13     1.85   2238   155                                       109  29       1.18     1.48   2268   246                                       110  30       1.23     1.51   3842   139                                       111  31       1.26     1.65   4263                                             112  32       1.75     1.23                                                    113  33       1.49     1.16   1918                                             114  34       1.30     1.43   2678                                             115  36       1.00     2.34   2150                                             116  37       1.01     2.22   4283                                             117  38       1.94     0.74   3300                                             118  52       0.96     2.34   2587   163                                       119  53       0.93     2.86   2301                                             120  54       1.07     1.94   2210   125                                       121  55       1.01     2.24   2213                                             122  56       1.04     2.19   2252                                             123  57       1.06     2.14   2552                                             124  58       1.28     1.41   2270                                             125  59       1.06     2.02   2267                                             126  60       1.06     2.09   2630                                             127  61       1.07     1.99   2507                                             128  62       2.48     0.53   2103                                             129  63       1.33     1.34   4630                                             130  64       1.12     2.15   1711                                             131  65       1.12     1.91   2310                                             132  66       1.01     2.37   2261                                             133  67       1.94     0.73   1980                                             134  66       0.91     3.08   2103                                             135  69       1.02     2.13   2981                                             136  70       1.07     1.86   2846                                             ______________________________________                                     

We claim:
 1. A pyridone dye of the formula (I): ##STR62## wherein: R¹ is hydrogen or C₁ -C₄ -alkyl;R² and R³ are identical or different and each is independently of the other, hydrogen, C₁ -C₁₂ -alkyl, C₁ -C₁₂ -alkyl substituted by cyano, phenyl, tolyl, C₁ -C₆ -alkanoyloxy, C₁ -C₄ -alkoxycarbonyl, C₁ -C₄ -alkoxycarbonyl substituted in an alkoxy group thereof by phenyl or C₁ -C₄ -alkoxy; C₄ -C₇ -cycloalkyl, phenyl, phenyl substituted by C₁ -C₄ -alkyl or C₁ -C₆ -alkoxyl; pyridyl, pyridyl substituted by C₁ -C₄ -alkyl or C₁ -C₆ -alkoxyl; C₁ -C₁₂ -alkanoyl, C₁ -C₁₂ -alkanoyl substituted by cyano, phenyl, tolyl, C₁ -C₆ -alkanoyloxy, C₁ -C₄ -alkoxycarbonyl, C₁ -C₄ -alkoxycarbonyl substituted in an alkoxy group thereof by phenyl or C₁ -C₄ -alkoxy; C₁ -C₁₂ -alkoxycarbonyl, C₁ -C₁₂ -alkylsulfonyl, C₁ -C₁₂ -alkylsulfonyl, substituted by cyano, phenyl, tolyl, C₁ -C₆ -alkanoyloxy, C₁ -C₆ -alkoxycarbonyl, C₁ -C₄ -alkoxycarbonyl, C₁ -C₄ -alkoxycarbonyl substituted in an alkoxy group thereof by phenyl or C₁ -C₄ -alkoxy; C₅ -C₇ -cycloalkylsulfonyl, phenylsulfonyl, phenylsulfonyl substituted by C₁ -C₄ -alkyl; pyridylsulfonyl, pyridylsulfonyl substituted by C₁ -C₄ -alkyl or C₁ -C₆ -alkoxyl; benzoyl, benzoyl, substituted by C₁ -C₄ -alkyl or C₁ -C₆ -alkoxyl; pyridylcarbonyl or thienylcarbonyl or are together with the nitrogen atom to which they are bonded unsubstituted or C₁ -C₄ -alkyl-substituted succinimido, unsubstituted or C₁ -C₄ -alkyl-substituted phthalimido or a heterocyclic ring selected from the group consisting or pyrrolidinyl, piperidinyl, morpholinyl, piperazinyl and N--C₁ -C₄ -alkyl-piperazinyl; X is --CH-- or --N--; Y is cyano or a radical of the formula CO--W, CO--OW or CO--NHW where W is hydrogen, C₁ -C₈ -alkyl which is unsubstituted or substituted by cyano, phenyl, tolyl, C₁ -C₆ -alkanoyloxy, C₁ -C₄ -alkoxycarbonyl, C₁ -C₄ -alkoxycarbonyl substituted in an alkoxy group thereof by phenyl or C₁ -C₄ -alkoxy; and which is ininterrupted or interrupted by one or two oxygen atoms in an ether function, C₅ -C₇ -cycloalkyl, phenyl or tolyl, and Z is a radical of the formula. ##STR63## wherein: n is 0 or 1; R⁴ is hydrogen, methyl, methoxy, C₁ -C₄ -alkylsulfonylamino, mono- or di-C₁ -C₄ -alkylaminosulfonylamino or the radical --NHCOR¹⁰ or --NHCO₂ R¹⁰, where R¹⁰ is phenyl, benzyl, tolyl or C₁ -C₈ -alkyl, which is uninterrupted or interruped by one or two oxygen atoms in an ether function; R⁵ is hydrogen, methyl, methoxy or ethoxy; R⁶ and R⁷ are identical or different and each is independently of the other hydrogen, C₁ -C₅ -alkyl, which is unsubstituted or substituted by cyano, phenyl, tolyl, C₁ -C₆ -alkanoyloxy, C₁ -C₆ -alkoxycarbonyl, C₁ -C₄ -alkoxycarbonyl, C₁ -C₄ -alkoxycarbonyl substituted in an alkoxy group thereof by phenyl or C₁ -C₄ -alkoxy; and which is uninterrupted or interrupted by one or two oxygen atoms in an ether function, C₃ -C₄ -alkenyl, C₅ -C₇ -cycloalkyl, phenyl or tolyl or are together with the nitrogen atom to which they are bonded a heterocyclic ring selected from the group consisting or pyrrolidinyl, piperidinyl, morpholinyl, piperazinyl and N--C₁ -C₄ -alkyl-piperazinyl; R⁸ is halogen; and R⁹ is hydrogen, halogen, C₁ -C₆ -alkyl, phenyl, phenyl, substituted by C₁ -C₄ -alkyl or C₁ -C⁶ -alkoxyl; benzyl, benzyl, substituted by C₁ -C₄ -alkyl or C₁ -C₆ -alkoxyl; cyclohexyl, thienyl, hydroxyl or mono-C₁ -C₈ -alkylamino; and R¹ is as defined above.
 2. The dye of claim 1, wherein said radical Z is selected from the group consisting of radicals IIc, IIj, IIl, IIm, IIn, IIo and IIp.
 3. The dye of claim 2, wherein said radical Z is of the formula IIc, IIj or IIl.
 4. The dye of claim 2, which is of the formula: ##STR64## wherein: X is --CH-- or --N--;L⁷ is C₁ -C₆ -alkyl, phenyl, tolyl, benzyl, cyclohexyl or thienyl; L¹ and L² are each independently of each other hydrogen, C₁ -C₈ -alkyl, phenyl, tolyl, C₁ -C₈ -alkylcarbonyl, C₁ -C₈ -alkylsulfonyl, phenylsulfonyl, tolylsulfonyl, pyridylsulfonyl, benzoyl, methylbenzoyl, pyridylcarbonyl or thienylcarbonyl; L³ is hydrogen, methyl, methoxy or the radical --NHCOR¹⁰ or --NHCO₂ R¹⁰, where R¹⁰, is phenyl, benzoyl, tolyl or C₁ -C₈ -alkyl, which is interrupted or uninterrupted by one or two oxygen atoms in an ether function; L⁴ and L⁵ are each independently of the other hydrogen, C₁ -C₈ alkyl, 2-cyanoethyl, benzyl, C₁ -C₄ -alkanoyloxy-C₁ -C₄ -alkyl, C₁ -C₄ -alkoxycarbaryl-C₁ -C₄ -alkyl or C₁ -C₄ -alkoxycarbonyloxy-C₁ -C₄ -alkyl; and L⁶ is hydrogen or methyl.
 5. The dye of claim 4, wherein X is --CH--. 